class_docstr: Dataset to manage the data loading, augmentation and generation. 
docstr: Get the size of dataset. 
docstr_tok: ["Get","the","size","of","dataset","."]
code: def __len__(self):
      """Get the size of dataset."""
      return len(self.lines)
  
file_path: nni/examples/nas/legacy/oneshot/pfld/datasets.py
imports: from __future__ import absolute_import, division, print_function
  import cv2
  import os
  import numpy
  from torch.utils import data
label_desc: Use image node_id 3 for calling the PFLDDatasets obj's underlying member method code with example usage: obj.__len__() and returns: len